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Functions
7.6 Motor control
Inverter with CU240B-2 and CU240E-2 Control Units
Operating Instructions, 07/2010, FW 4.3.2, A5E02299792B AA
171
7.6.1.2
Additional characteristics for the V/f control
In addition to linear and square-law characteristics, there are the following additional
versions of the V/f control that are suitable for special applications.
Table 7- 13 Additional V/f control versions (P1300)
Parameter
Application
P1300 = 1
Linear V/f characteristic with Flux Current Control (FCC)
Voltage losses across the stator resistance are automatically compensated. This is
particularly useful for small motors since they have a relatively high stator resistance.
The prerequisite is that the value of the stator resistance in P350 is parameterized as
accurately as possible.
P1300 = 3
Freely adjustable V/f
characteristic, which
supports the torque
behavior of
synchronous motors
(SIEMOSYN motors)
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P1300 = 4
P1300 = 7
Linear V/f characteristic with ECO
Square-law V/f characteristic with ECO
ECO mode is suitable for applications requiring a lower level of dynamic performance
and a constant speed setpoint and delivers an energy saving of up to 40 %.
When the setpoint is reached and remains unchanged for 5 s, the inverter
automatically reduces its output voltage to optimize the motor's operating point. ECO
mode is deactivated in the event of setpoint changes or if the inverter's DC-link
voltage is too high or too low.
In ECO mode set the slip compensation (P1335) to 100 %. In the event of minor
fluctuations in the setpoint, you have to raise the ramp-function generator tolerance
using p1148.
Note: Sudden load variations can cause the motor to stall.
P1300 = 5
P1300 = 6
Linear V/f characteristic for textile applications where it is important that the motor
speed is kept constant under all circumstances. This setting has the following effects:
1.
When the maximum current limit is reached, the stator voltage is reduced but not
the speed.
2.
Slip compensation is locked.
P1300 = 19
V/f control without characteristic. The interrelationship between the frequency and
voltage is not calculated in the inverter, but is specified by the user. With BICO
technology, P1330 defines the interface via which the voltage setpoint is entered
(e.g. analog input → P1330 = 755).
For more information about this function, see function diagram 6300 in the List Manual.